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Shows the influence of CdS particles Concentration

Results and discussion Fig 1 shows the influence of CdS particles concentration in supporting electrolyte on the surface morphology of the coatings formed after 2 min of PEO processing Surface morphology is not significantly influenced by the concentration of CdS particles in supporting electrolyte Numerous microdischarge channels of varying diameter as well as regions resulting from the rapid cooling of molten material decorate the surface of the coatings Since the concentration of CdS particles in PEO coatings was either close to or below the detection limit of EDS system we used wavelength dispersive XRF measurement to obtain Ti Cd ratio XRF measurements confirmed that content of CdS in coatings increases with increasing CdS particle concentration in supporting electrolyte Table 1 XRD pattern of pure CdS powder and XRD patterns of coatings formed in supporting electrolyte with addition of various concentrations of CdS particles are shown in Fig 2 The peaks observed in XRD patterns of CdS particles at 2 θ values of 26 5 43 8 and 51 9 unambiguously matched 111 220 and 311 crystalline planes of the face centered cubic structure of CdS PDXL DB Card No 9008839 Fig 2 shows that obtained coatings are well crystallized with clearly pronounced diffraction peaks corresponding to anatase phase of TiO2 PDXL DB Card No 9008213 which is photocatalytically active phase Elemental Ti originates from the substrate due to penetration of X rays through the porous surface layer and reaching the substrate The absence of visible peaks of CdS in XRD patterns could be a consequence of the low concentration of uniformly dispersed CdS particles all over the TiO2 surface coatings In order to investigate whether CdS particles are present in TiO2 coatings we performed Raman measurements Fig 3 Raman spectrum of CdS powder Fig 3a is characterized by a strong band at about 296 cm 1 assigned to the first order longitudinal optical phonon 1LO and the peak at about 592 cm 1 corresponding second order 2LO optical phonons 20 

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